CVE-2026-9087
Keycloak: cross-session email verification proof not bound to upstream identity in first-broker-login
CVSS Score
6.4
EPSS Score
0.3%
EPSS Percentile
21th
A flaw was found in Keycloak. The cross-session verification proof is keyed only by (local userId, idpAlias) and is not bound to the upstream identity that was actually verified, so a second upstream account on the same IdP can consume it and get linked to the victim's local account.
| CWE | CWE-639 |
| Vendor | red hat |
| Product | red hat build of keycloak 26.4 |
| Published | May 20, 2026 |
| Last Updated | Jun 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4.13
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6.3
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2026:25097 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:25098 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:30049 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:30050 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-9087 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2480172